There are a wide range of circumstances in which fluid must be transferred from one place to another. For instance, in a scientific laboratory, a pipette is commonly used to transfer a fluid (such as blood) from a beaker to a test tube, or from one test tube to another.
Current devices for drawing fluid generally include a reservoir for storing the fluid, a fluid inlet/outlet orifice through which fluid can be drawn, and a compressible hand pump. In use, the pump is compressed, which forces air out through the inlet/outlet orifice. The orifice is then inserted into the fluid source (from which fluid is to be drawn), and the pump allowed to decompress. This draws air from the reservoir, reducing the pressure in the reservoir and thereby drawing fluid in through the inlet/outlet orifice. To expel fluid from the device, the pump is compressed again. This increases the pressure in the reservoir and forces fluid back out through the inlet/outlet orifice.
Current devices suffer from the disadvantage that the pump cannot be repeatedly compressed and decompressed, to draw more fluid, because each compression will force the drawn fluid out of the inlet/outlet orifice. These devices are not capable of retaining fluid which has been drawn, which makes it difficult to draw an exact volume as required.
It is an object of the present invention to reduce or eliminate some or all of the disadvantages of conventional devices for drawing fluid.